The present invention generally relates to storage systems, and more particularly to reclamation of storage media in storage systems.
A linear tape file system (LTFS) is software that allows for performing standard file operations to tape media (a type of sequential access media) and providing an intuitive interface to users to manipulate files or directories on the tape media. Several implementations of LTFS have been developed for tape drives and tape libraries. Hierarchical storage systems integrating a clustered file system with LTFS have been also developed, in which part of files in the clustered system are stored on tape media in the LTFS format.
Although LTFS can present tape media as disk-like drives, a tape medium may not allow for random accessing as the tape medium is sequential in nature. New data may be appended to the tape medium. Data deletions may just erase pointers to the data. As such, space on the tape medium that is occupied by deleted data may not be reused during normal operations.
Reclamation is a process by which active data on one or more tape media are consolidated onto another tape medium by reading the active data stored in a source tape medium and writing the read data into a destination tape medium. The reclamation process can be performed so that all active data stored in the source tape medium with low usage is moved to another tape medium to improve overall tape usage, for instance. The reclaimed tape medium becomes a scratch tape where no active data remains and can be reformatted to reuse. The reclamation can be performed so that all active data stored in the source tape medium is moved to another tape medium that has different recording density and/or different transfer rate due to difference in generations between these tape media, for example.